Insulated structure including cavities holding aerogel connected to a vacuum sustaining unit

ABSTRACT

A thermal insulation system includes an evacuated structure having an internal space filled with an aerogel layer, in which a vacuum is sustained by a vacuum pump operating when it is determined that a pressure within the internal space has risen to a predetermined level. For example, such a system is used within a dome structure extending over and around a heat receiving structure within a solar heating system or within a system providing thermal insulation for a building structure, a refrigerator, or a railroad car.

RELATED APPLICATIONS

This is a continuation-in-part of a copending U.S. patent application Ser. No. 12/592,085, filed Nov. 19, 2009. This application claims the benefit of a prior-filed U.S. Provisional Patent Application No. 61/395,886, filed May 18, 2010 and of U.S. Provisional Patent Application No. 61/463,703, filed Feb. 22, 2011.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to thermal insulation systems, more particularly to such systems including evacuated structures, and yet more particularly to the use of such systems to allow heat retention within solar heat collectors, and to the use of such systems to prevent a transfer of heat into or away from an interior space.

2. Summary of the Background Information

A solar heat collector typically includes a heat receiving structure through which a fluid, such as water, is circulated to be heated by solar radiation. The heat receiving structure comprises elements such as piping, tubing, a reservoir tank, and a thermally conductive structure to absorb heat from radiant energy and to transmit the heat to the fluid. Preferably, a translucent cover is placed over the heat receiving structure, allowing the passage of radiant energy, so that the vessel is heated by sunlight, while minimizing the conduction of heat, allowing the heat receiving structure to rise to a relatively high temperature without substantial heat losses to the atmosphere around the solar heat collector. The effectiveness of the thermal insulation in preventing heat loss to the atmosphere has a significant effect on the overall efficiency of the solar heat collector, particularly when the solar heat collector is operated in a cold climate.

One method that has been applied to provide thermal insulation while allowing the transmission of radiant energy is the use of a pair of glass plates that are spaced apart to form an intervening air space. A single plate of glass has an insulation value of R1, with this value being increased to R2 when a second plate is installed to provide a separate air space. Evacuating the air within the space between the glass plates can provide substantially higher insulation values of R30 to R50, at the cost of a need to provide air tight seals around the edges of the glass plates and of a need to provide a structure that can withstand a pressure of about 15 psi acting on each of the plates. However, the use of structures including evacuated spaces for thermal insulation has been the brittleness and relatively low strength of the glass materials generally used and by a lack of reliability of such structures in large thermally insulating systems because small leaks result in a loss of vacuum.

The patent literature includes a number of descriptions of structures for reducing the transfer of heat through the use of spaced-apart glass plates on opposite sides of an evacuated space. For example, U.S. Pat. No. 2,216,332 describes a window including a pair of spaced-apart glass plates and a pipe extending within the wall from the space between the glass plates. The pipe extends to a valve that can be opened to withdraw air form the space between the plates or to return air to this space. A supporting structure, composed of slotted, interlocking vertical and horizontal spacers dividing the space between the plates into a number of smaller rectangular spaces, extends between the plates to help resist the atmospheric pressure acting on the plates when air is removed from this space.

U.S. Pat. No. 3,990,201 describes an evacuated dual pane window structure is provided for reducing heat loss through the window structure. The window structure comprises a pair of closely spaced panes of glass having a spacing of less than 0.25 inch with a spacer means positioned between and uniformly spaced in the area between the panes, and sealing means such as an O-ring positioned around the perimeter and between the panes of glass. A vacuum=pump may be provided for evacuating the area between the panes of glass for reducing thermal losses through the window structure. Reflective coatings may; be provided on the inside surfaces of the glass. A plurality of windows of the above structure may be connected by manifold piping to a single vacuum pump, which is actuated by a thermostat when a preset temperature differential exists between the outside and the inside of the building where the windows are used.

U.S. Pat. No. 4,184,480 describes a conventional flat plate solar heat collector pro-vided with a contoured vacuum insulation window supported solely about its peripheral edge portions. The window is a composite formed from a pair of minimum thickness complementarily contoured glass sheets, which with the exception of their peripheral portions which are sealed together, are spaced apart from one another so as to provide an evacuated chamber therebetween and thus insulate one sheet from the other. The window formed by the nested or complementary contoured glass sheets is contoured in both its longitudinal and lateral directions, such that in its longitudinal direction the window is composed of a plurality of sinusoidal corrugations whereas in its lateral direction the peaks of such corrugations are contoured in the form of paraboloids so as to provide maximum uniform tensile strength to the window such that it may withstand the forces generated thereon by the atmosphere. However, the size of the insulated glass member is limited by the forces, principally caused by the air pressure acting on the two glass sections, and possibly additionally by manufacturing and transportation difficulties associated with handling and forming large pieces of glass. What is needed is a method for a way to provide a thermally insulating cover over a larger and taller solar heat collector.

Other patents describe methods for sealing the interface between glass plates and structural framing members and for providing channels for the evacuation of air between the glass plates to form thermally insulating structures. For example, U.S. Pat. No. 6,383,580 describes a vacuum insulating glass (IG) unit and method-of making the same. An edge-mounted pump-out structure is provided, including a pre-positionable insert capable of receiving a pump-out tube therein. Following formation of the edge-mounted pump-out structure and its positioning on the unit, an edge seal is formed for hermetically sealing off the low pressure space located between the substrates.

U.S. Pat. No. 6,506,272 describes a vacuum insulating glass (IG) unit. In certain embodiments, the internal cavity is evacuated (i.e., pumped out) via a pump-out aperture. A cover with one or more sealing element(s) may be provided over the pump-out aperture so that during the pump-out process air flows out of the internal cavity and through space(s) between adjacent sealing elements or sealing element portions. Following evacuation or pumping out, the sealing element(s) is/are heated and the sealing member may be pressed downwardly toward the substrate. This causes the heat-softened sealing element(s) to expand horizontally and merge with one another so as to form a hermetic seal around the pump-out aperture and between the sealing member and the substrate.

U.S. Pat. No. 5,902,652 describes a method for providing pillars to space apart thermally insulating glass panels that are spaced apart, a method for providing an improved edge seal around the glass panels, and a method for providing an improved pump-out tube for use during construction of the panels.

The patent literature includes a number of descriptions of the use of aerogel layers to provide mechanical support within panel assemblies having spaced-apart panels, with the space between the panels being filled by aerogel. Examples of such panel assemblies range from small windows in opto-electronic devices to large windows in buildings. The patent literature additionally includes a number of descriptions of processes for manufacturing aerogels.

An aerogel was first created by Samuel Stephens Kistler in 1931. Aerogels are produced by extracting the liquid component of a gel through supercritical drying, allowing a liquid content of the gel to be slowly drawn off without causing the solid matrix in the gel to collapse from capillary action. While the first aerogels were produced from silica gels, Kistler later made aerogels based on alumina, chromic, and tin oxide. Carbon aerogels were first developed in the late 1980's.

SUMMARY OF THE INVENTION

Various difficulties and shortcomings of prior-art thermally insulating systems including evacuated spaces are overcome through the use of the present invention. A dome-shaped central space within a thermally insulating system is provided for holding the heat-receiving portion of a solar heating system. The mechanical weakness of panels extending adjacent evacuated spaces is overcome by providing aerogel layers within the evacuated spaces to keep the panels from being pulled together as the spaces are evacuated. Aerogels are manufactured materials having the lowest bulk density of any known porous solid, being derived from a gel in which a liquid component is replaced by a gas, resulting in an extremely low density porous solid that is particularly affected as a thermal insulator. Because of the porosity of the material, a vacuum can be readily achieved within an aerogel layer. The use of a vacuum instead of air or another gas within the porous layer further enhances the thermal insulation properties of the layer. In applications where transparency is not needed, a strong and resilient material, such as a metal, is used in place of the glass. The reliable, long-term use of large thermally insulating systems is achieved through the use of vacuum sustaining units to make the systems tolerable of small leaks.

In accordance with a first aspect of the invention, a thermally insulating system is provided. The thermally active system includes a thermally insulating structure includes an internal space formed by internal surfaces; an aerogel layer, and a vacuum sustaining unit. The aerogel layer extends between at least parts of the internal surfaces within the internal space. The vacuum sustaining unit including a first input tube connected to the internal space, a pressure sensor sensing a pressure within the internal space; and a vacuum pump evacuating air from the internal space in response to a signal from the pressure sensor indicating that a pressure within the internal space has risen above a predetermined level.

In accordance with a second aspect of the invention, solar heating apparatus is provided, including a heat receiving structure, through which a fluid flows to be heated by solar radiation; and a thermally insulating structure. The thermally insulating structure includes a floor structure and a dome-shaped structure, extending upward from the floor structure. The dome-shaped structure includes an internal surface forming a central space holding the heat-receiving structure and extending from the internal surface to the floor structure. The dome-shaped structure also includes at least one outward-facing surface coated with a selective material having a thermal absorption that is significantly greater than its thermal emissivity.

In first and second embodiments of the invention, the thermally insulating structure includes a floor structure and a dome-shaped structure, extending upward from the floor structure, and the dome-shaped structure includes an internal surface forming a central space extending from the internal surface to the floor structure, and an external surface. The internal space extends within the dome-shaped structure, separate from the central space and between the internal and external surfaces, and the dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure. The floor structure may include a flat inner plate and a flat outer plate, each composed of a strong and resilient material; a frame holding these plates in a spaced-apart relationship, an aerogel layer, and a second input tube. The frame forms an inner space extending within the frame and between the flat inner and outer plates, with the aerogel layer being held within the inner space, extending within the frame and between the flat inner and outer plates; and with the second input tube connecting the inner space within the floor structure with the vacuum sustaining unit. The thermally insulating system may additionally include a conduit connecting the central space with an external space.

In the first embodiment of the invention, the dome-shaped structure includes an inner dome, an outer dome, a gasket, and at least one bracket. The inner dome includes a dome-shaped portion having an inner surface forming the internal surface, an outer surface, and a lower surface, with a lower flange extending outwardly around the lower surface. The outer dome includes a dome-shaped portion having an inner surface, an outer surface forming the external surface, and a lower surface, upwardly disposed from the lower flange of the inner dome, with an upper flange extending outwardly around the lower surface of the outer dome. The gasket extends between the lower flange and the upper flange to enclose a space extending between the inner and outer translucent domes to form the internal space; and the bracket(s) hold the inner and outer translucent domes in a spaced-apart relationship. At least one of the outer surfaces may be coated with a selective material having a thermal absorption that is significantly greater than its thermal emissivity, with both the inner and outer domes being composed of a translucent material, or with at least one of these domes being composed of an opaque material. (As the term is used herein, “translucent” materials are understood to include transparent materials.)

In the second embodiment of the invention, the dome-shaped structure includes a dome-shaped framework including a plurality of frame openings, and an inner sheet and an outer sheet held within each of the frame openings. The inner and outer translucent sheets are held in a spaced-apart relationship to form a portion of the internal space, with an aerogel layer extending within each portion of the internal space. The portions of the internal space in adjacent frame openings are connected by openings within the framework to form the internal space. The dome-shaped framework may additionally include a door section mounted to be moved between an open position and a closed position, and a flexible tube extending between the door and an adjacent surface of the dome-shaped framework. Access from outside the dome-shaped structure to the central space within the dome-shaped structure is then provided with the door section in the open position and prevented with the door section in the closed position. The door section then extends around one of the frame openings, holding the inner and outer sheets within the frame opening in the door section, while the flexible hose connects the portion of the internal space between the inner and outer translucent curved sheets within the frame opening in the door section with the portion of the internal space within an adjacent frame opening. The dome-shaped framework may additionally include an opening through which a lens concentrates solar radiation within the central space. The inner sheet and the outer sheet held within each frame opening may be composed of a translucent material, or at least one of these sheets may be composed of an opaque material, with at least one of the outer surfaces being coated with a selective material having a thermal absorption that is significantly greater than its thermal emissivity.

In the third embodiment of the invention, the thermally insulating structure comprises a plurality of thermally insulating panels, each including a flat inner plate composed of a strong and resilient material, a flat outer plate composed of a strong and resilient material, and a frame holding the flat inner and outer plates in a spaced-apart relationship while forming an inner space extending within the frame and between the flat inner and outer plates. A portion of the aerogel layer extends between the flat inner plate and the flat outer plate within each of the thermally insulating panels. The interior space within each of the thermally insulating panels is connected to the vacuum sustaining unit. The interior space within each of the thermally insulating panels may be connected to the vacuum sustaining unit by a common evacuation tube, or interior spaces within adjacent thermally insulating panels are connected by openings extending through adjacent portions of the frames within the adjacent thermally insulating panels. The thermally insulating panels may form a box structure, extending around a central space, and a door structure, with the box structure including as access opening, and with the door structure being movable between a closed position, extending within the first access opening, and an open position. Access into the central space is provided with the door structure in the open position and prevented with the door structure in the closed position. The door structure includes one of the thermally insulating panels, connected to the vacuum sustaining unit by a path including a flexible hose. Such a box structure may be used within a refrigerator, a container, or a railroad car.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a partly sectional plan view of a solar heat collector built in accordance with a first embodiment of the invention;

FIG. 2 is a cross-sectional elevation of the solar heat collector of FIG. 1, taken as indication by section lines 2-2 therein, showing elements of a first fluid path therein;

FIG. 2A is a fragmentary cross-sectional elevation of the solar heat collector of FIG. 1, taken as indication by section lines 2-2 therein;

FIG. 3 is a cross-sectional elevation of the solar heat collector of FIG. 1, taken as indication by section lines 2-2 therein, showing elements of a second fluid path therein;

FIG. 4 is a partly sectional plan view of the solar heat collector of FIG. 1, showing fluid paths therein;

FIG. 4A is a cross-sectional elevation of a vacuum sustaining unit within the solar heat collector of FIG. 1;

FIG. 5 is a partly sectional plan view of a solar heat collector having a smaller diameter transverse hose;

FIG. 6 is a fragmentary elevation of a frame within the solar heat collector of FIG. 1, taken in a direction perpendicular to an interconnection axis therein;

FIG. 6A is a fragmentary elevation of a frame within the solar heat collector of FIG. 1, taken in a direction parallel to an interconnection axis therein;

FIG. 7 is an elevation showing a process for winding a transverse hose around a frame within the solar heat collector of FIG. 1;

FIG. 8 is a perspective view of a solar heat collector built in accordance with a second embodiment of the invention.

FIG. 9 is a partly sectional plan view of a dome-shaped structure within the solar heat collector of FIG. 8;

FIG. 10 is a transverse cross-sectional view of a frame member within the dome-shaped structure of FIG. 9;

FIG. 11 is a first transverse cross-sectional view of a frame member at a removable frame section within the dome-shaped structure of FIG. 9;

FIG. 12 is a second transverse cross-sectional view of the frame member of FIG. 11;

FIG. 13 is a fragmentary cross-sectional plan view of a dome-shaped structure including an access door, for alternative use within the solar heat collector of FIG. 8;

FIG. 14 is a first transverse cross-sectional view of a frame member pivotally mounting the access door of FIG. 13;

FIG. 15 is a transverse cross-sectional view of a frame member latching the access door of FIG. 13;

FIG. 16 is a second transverse cross-sectional view of the frame member of FIG. 14;

FIG. 17 is a third transverse cross-sectional view of the frame member of FIG. 14;

FIG. 18 is a perspective view of a dome-shaped structure including a lens concentrating solar radiation within a solar heat collector disposed therein;

FIG. 19 is a fragmentary perspective view of a dome-shaped structure including an opening concentrating solar radiation within a solar heat collector disposed therein;

FIG. 20 is a perspective view of a dome-shaped structure including a Fresnel lens concentrating solar radiation within a solar heat collector disposed therein.

FIG. 21 is a fragmentary cross-sectional elevation of the Fresnel lens of FIG. 21;

FIG. 22 is a plan view of portions of a floor structure within the thermal insulation system of FIG. 5, showing the portions in an exploded relationship;

FIG. 23 is a fragmentary perspective view of a frame within the thermal insulation system of FIG. 8:

FIG. 23A is a fragmentary perspective view of a first alternative version of the frame of FIG. 8;

FIG. 23B is a fragmentary perspective view of a second alternative version of the frame of FIG. 8;

FIG. 24 is a plan view of an elongated version of the dome-shaped structure of FIG. 9;

FIG. 25 is a fragmentary cross-sectional view of a panel assembly within the dome-shaped structure of FIG. 9;

FIG. 26 is a fragmentary cross-sectional view of an alternative panel assembly for use within the dome-shaped structure of FIG. 9;

FIG. 26A is a fragmentary cross-sectional view of a panel assembly including a single opaque panel for use within a solar heat collector;

FIG. 27 is a cross-sectional end elevation of a thermally insulating panel used within a third embodiment of the invention;

FIG. 28 is a fragmentary front elevation of a thermal insulation system including a number of the insulating panels of FIG. 27 extending along a wall;

FIG. 29 is a fragmentary front elevation of a thermal insulation system including a number of the insulating panels of FIG. 27 extending within a wall;

FIG. 30 is a cross-sectional plan view of a refrigerator including versions of the insulating panel of FIG. 27;

FIG. 31 is a first cross-sectional end elevation of the refrigerator of FIG. 30, taken as indicated by section lines 31-31 therein;

FIG. 32 is a second cross-sectional end elevation of the refrigerator of FIG. 30, taken as indicated by section lines 31-31 therein;

FIG. 33 is a cross-sectional plan view of a container including versions of the insulating panel of FIG. 27;

FIG. 34 is a first fragmentary cross-sectional elevation of the container of FIG. 33 showing a first method for connecting the insulating panels therein;

FIG. 35 is a second fragmentary cross-sectional elevation of the container of FIG. 34 showing a second method for connecting the insulating panels therein; and

FIG. 36 is a cross-sectional plan view of a railroad car including versions of the insulating panel of FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

A solar heat collector typically includes a heat receiving structure through which a fluid, such as water, is circulated to be heated by solar radiation. The heat receiving structure comprises elements such as piping, tubing, a reservoir tank, and a thermally conductive structure to absorb heat from radiant energy and to transmit the heat to the fluid. Preferably, a translucent cover is placed over the heat receiving structure, allowing the passage of radiant energy, so that the vessel is heated by sunlight, while minimizing the conduction of heat, allowing the heat receiving structure to rise to a relatively high temperature without substantial heat losses to the atmosphere around the solar heat collector. The effectiveness of the thermal insulation in preventing heat loss to the atmosphere has a significant effect on the overall efficiency of the solar heat collector, particularly when the solar heat collector is operated in a cold climate or if it is desired to operate the solar heat collector at a relatively high temperature needed for the production of mechanical power to drive an electrical generator. For example, U.S. Pat. No. 7,870,855, the disclosure of which is incorporated herein by reference, describes a solar heating system including dome-shaped apparatus that is heated by solar radiation. Other descriptions of solar heating systems including dome-shaped heat receiving structures are found in the disclosures of U.S. Pat. Nos. 4,057,048, 4,136,670, 4,305,383, and 5,427,628, each of which is incorporated herein by reference.

A solar heat collector having a dome-shaped structure built in accordance with a first embodiment of the present invention will first be discussed with reference being made to FIGS. 1-7. FIG. 1 is a plan view of the solar heat collector 100, while FIG. 2 is a cross-sectional elevation thereof, taken as indicated by section lines 2-2 in FIG. 1. The solar heat collector 100 includes a frame 102 having a plurality of legs 104, a transverse hose 106 winding around the frame 102 and between the legs 104, and a reservoir 108, all held within a translucent dome structure 110.

Within the frame 102, each of the legs 104 includes a pair of tubes 112, disposed in a circular pattern 113 around a central axis 114 of the hybrid solar heat collector 100 and extending upward, in the direction of arrow 116 and inward, toward the central axis 114. The legs 104 include an inlet/outlet leg 115, in which the tubes 112 are connected to an inlet tube 117 and an intermediate tube 118, and a number of interconnected legs 119. In each of the interconnected legs 119, the tubes 112 are connected at a lower end 120 by connection elements 122. Tubes 112 within adjacent legs 104 are connected at an upper end 124 by connection elements 126, forming a first fluid path 128 extending through the frame 102 from the inlet tube 117 to the intermediate tube 118. In this way, various tubular elements are used both as tubes forming the first fluid path 128 and as struts forming the structure of the frame 102. It is understood that the connections between tubes 112 in individual legs 104 may alternately be made at the upper ends 124, with connections between tubes in adjacent legs 104 being made at the lower ends 120.

In a system heating water for domestic use, the first fluid path 128 within the inlet tube 130 is connected to an inlet water tube 140 through an anti-scald valve 142, and to the reservoir 108 through an intermediate tube 118. The reservoir 108 includes a heater 145, such as an electrical heating element 146 that is connected to an electrical inlet 148 in response to a thermal switch 150. A reservoir outlet tube 152 from the reservoir 108 is connected to an outlet water tube 154 through the anti-scald valve 142. For example, the thermal valve 150 is set to turn the heating element 146 on when the temperature of water within the reservoir 108 is below 90 degrees F., so that hot water can be provided under conditions in which heating by solar radiation alone is insufficient, and additionally so that a space 156 within the translucent dome structure 110 is sufficiently heated by the reservoir 108 to prevent the freezing of water in the first fluid path 128 through the frame 102. The anti-scald valve 142 senses the temperature of water flowing into the outlet water tube 154. When the temperature is below a potentially scalding level, such as, for example, 49 deg C. (120 deg F.), water flows from the inlet water tube 140 to the inlet tube 132 within the frame 104 and from the reservoir outlet tube 152 to the outlet water tube 154. When this temperature is at or above this potentially scalding level, water from the inlet water tube 140 is mixed with water from the reservoir outlet tube 152 within the anti-scald valve 142, with the resulting mixture being delivered through the water outlet tube 154.

The dome structure 110 includes an outer dome 160 and an inner dome 162, between which a space 164 is provided to reduce a loss of heat from a central space 156 within the inner dome 162 to the surrounding atmosphere 166. Preferably, a partial vacuum is maintained within the space 164 by a vacuum sustaining unit 167. Preferably, structural support between the outer dome 160 and the inner dome 162 is provided by an aerogel layer 168 extending within the space 164 between the domes 160, 162. Each of the domes 160, 162 includes an outward extending flange 169, which is held in place on a floor 170 of the hybrid solar heat collector 100 by a number of brackets 172 fastened to the floor 170 with a number of screws 174. A gasket 173 disposed between the flange 169 of the outer dome 160 and the flange 169 of the inner dome 162 seals the space 164 between these domes 160, 162, with the gasket 173 being compressed as the screws 174 are tightened.

FIG. 2A is a fragmentary cross-sectional elevation of the dome structure 110, taken as indicated by section line 2A-2A in FIG. 1, showing an alternate construction for the flanges 169, which may be formed as integral portions of the translucent domes 116, and 118, as shown in FIG. 2, or as separate structures rigidly attached to the hemispherical portions 175 of the domes 116, 118, as shown in FIG. 2A. The vacuum sustaining unit 167 is connected to the space 164 between the domes 160, 162 through a tube 175 a extending through the gasket 173.

A central portion 179 of the transverse hose 106 is wound in a continuous, generally spiral, form around the frame 102 from a lower turn 180 to an upper turn 182, with a number of intermediate turns 184 extending therebetween. In FIG. 1, only one of these intermediate turns 184 is shown to provide a clear view of other elements within the solar heat collector 100. The legs 104 of the frame 102 include an equal number of inner frame legs 186 and outer frame legs 188, alternately disposed around the frame 102, with each turn 180, 182, 184 of the transverse hose 106 being alternately disposed outside the inner frame legs 186 and inside the outer frame legs 188. In general, the inner frame legs 186 and the outer frame legs 188 may be disposed outward from the central axis 114 through different distances to provide suitable angles of wrap for the transverse hose 106 around the inner frame legs 186 and the outer frame legs 188. In the example of FIGS. 1 and 2, the outer legs 188 are disposed farther away from the central axis 114 than the inner legs 186.

FIGS. 3 and 4 show portions of a second fluid path 187, formed by the transverse hose 106 extending outward from the hybrid solar heat collector 100, with FIG. 3 being a fragmentary elevation, and with FIG. 4 being a fragmentary plan view. In both FIGS. 3 and 4, the translucent dome 110 is shown in cross-section to avoid obscuring the structures being shown. A first connection portion 190 of the transverse hose 106 extends outward, in the direction of arrow 192, from the lower turn 180, while a second connection portion 194 extends outward, additionally in the direction of arrow 192, from the upper turn 182. The transverse hose 106 forms a continuous second fluid path 196, through which a fluid can be pumped in either direction, with either the first connection portion 190 or the second connection portion 194 providing an inlet to the hybrid solar heat collector 100 while the other connection portion 190, 194 provides an outlet therefrom.

The transverse hose 106 is composed, for example, of a metal or thermoplastic material having an outwardly extending stiffening structure 198, such as corrugations, bellows, or a helical element extending along the transverse hose 106, which function to allow the transverse hose 180 to retain its circumferential stiffness (i.e. to remain round while avoiding collapsing) when the hose 106 is bent sharply. The transverse hose 106 may be formed as an integral plastic or metal tubular structure by molding or forming, or as a fabricated structure, such as a structure fabricated from a number of metal parts or a plastic tube attached to extend along a metal helical spring. This type of structure allows the transverse hose 106 to be of a diameter sufficiently large to permit the flow of a gas, such as air, through the transverse hose 106, to be heated directly within the solar heat collector 100 without a need for a separate path through which a liquid is pumped and a heat exchanger to heat the air from the liquid.

Preferably, the solar heat collector 100 includes an insulated floor structure 200 formed as a thermally insulating vacuum panel structure including the floor 170, a lower plate 201, and a frame 202, which are attached and sealed to one another so that an internal space 203 is formed, with the internal space 203 being evacuated by the vacuum sustaining unit 167 through an evacuation tube 204 (shown in FIG. 1), extending through the floor 170. Preferably, the floor 170 and the lower plate 201 are each flat a flat plate composed of a tough, resilient material, such as a metal or a reinforced plastic, since transparency is not needed. The floor structure 200 may also include a number of spacers 206 extending between the floor 170 and the lower plate 201 to resist the tendency of the pressure acting thereon to push the floor 170 and the lower plate 201 together. The spacers 206 may, for example, be cylindrical or elongated. The floor structure 200 may also include a number of hollow spacers 207 provided for the passage of hoses and tubes forming part of the fluid paths 128, 187 through the floor structure 200.

It is noted that the shape of the hemispherical portions 175 of each of the translucent domes 116, 118 is considered ideal for resisting internal and external pressure. Evidence of this is seen in the design of tanks for storing gas at relatively high internal pressures, which are generally spherical or cylindrical with hemispherical ends, and in the design of deep diving equipment, including diving helmets and submersible vehicles, which generally include spherically shaped surface for resisting high external pressures. The aerogel layer 168 provides additional resistance to the forces pulling the domes 116, 118 together as a partial vacuum is applied by the vacuum sustaining unit 167. Nevertheless, if additional structure is needed to maintain the space 132 between the translucent domes 116, 118, spacers (not shown) may be attached to extend between the translucent domes 116, 118.

FIG. 4A is a schematic view of the vacuum sustaining unit 167, built in accordance with the invention for use in a thermally insulating system including evacuated spaces, such as the thermally insulating system 110 described above in reference to FIGS. 1-4. The vacuum sustaining unit 167 includes an input tube 210 attached, for example, to the evacuation tubes 175 a, 204 of the thermal insulation system 110. The vacuum sustaining unit 167 additionally includes a vacuum pump 211, which pulls air from the input tube 210 to be expelled through an opening 212 in the a housing 213. Preferably, a check valve 214 allows the outward movement of air, in the direction of arrow 216 while preventing a reverse flow of air, opposite the direction of arrow 216. A pressure sensor 217 may also be included, turning on the vacuum pump 211 when the pressure within the input tube 210 is above a predetermined level and turning the vacuum pump 211 off when the pressure within the input tube 172 is low enough. The pressure sensor 217 may also provide an input signal to operate an indicator light 218, turning on the indicator light 218 when the vacuum pump 211 is being driven. For example, a constantly running vacuum pump 211 would mean that the vacuum sustaining unit 167 could not keep up with an air leak, indicating a need for repairs.

While, in the example of FIG. 4A, the pressure sensor is shown within the housing 178 of the vacuum sustaining unit 167 to measure a pressure within the interior space 132 of the dome-shaped structure 112 by its effect on the pressure within the input tube 172, which is connected to the interior space 132, it is understood that the pressure sensor 184 may alternatively be placed within the interior space 132 to measure this pressure directly. It is additionally understood that additional indicator lights 144 may be connected to the vacuum sustaining unit 167 through wired or wireless connections to provide similar indications at various locations.

Thus, through operation of the vacuum sustaining unit 167, the dome shaped structure 110 and the floor structure 126 become evacuated structures, with air being evacuated from the internal space 132 of the dome-shaped structure 110 and the internal space 148 of the floor structure 126. As the term is used herein, the evacuation of air does not mean that a perfect vacuum is achieved or approximated, but rather that a pressure low enough to substantially reduce the transfer of heat is achieved.

Referring again to FIG. 2, the solar heat collector 100 preferably additionally includes a conduit 218 a connecting the central space 156 within the inner dome 162 with a space 166 outside the dome structure 110. For example, the conduit 218 a may carry electrical wires to a power source or a control system. The conduit 218 a prevents the formation of a substantial vacuum within the central space 156 in the event that a leak occurs between the internal space 132 of the dome-shaped structure 110 and the internal space 148 of the floor structure 126, preventing a possible structural failure of the dome-shaped structure 110.

FIG. 5 is a partly sectional plan view of an alternative solar heat collector 219 built in accordance with the invention to include a smaller-diameter alternative transverse hose 220, which does not include the outwardly extending stiffening structure 198 of transverse hose 106. This smaller diameter transverse hose 220 may be used to heat a liquid, such as water, flowing at an appropriate speed. Like the transverse hose 106, the alternative transverse hose 220 is wound around a frame 221 in a number of turns 222, which are each disposed outwardly from a number of inner frame legs 223 and inwardly from a number of outer frame legs 224. For clarification, an upper turn 225 and a lower turn 226 of the alternative transverse hose 220 are shown in the drawing, with only one of a number of the intermediate turns 227 being shown. A first connection portion 228 of the alternative transverse hose 220 extends from the upper turn 225, while a second connection portion 230 thereof extends from the lower turn 222. When the frame 214 of the alternative solar heat collector 210 is compared to the frame 102 of the solar heat collector 100, it is noted that, in the frame 214, the outer frame legs 218 are displaced inwardly relative to the inner frame legs 217. This is necessary so that the smaller-diameter alternative transverse hose 212 can wrap partly around both the inner frame legs 217 and the outer frame legs 218.

FIGS. 6 and 6A are fragmentary elevations of the frame 102, showing the connection 262 between a straight tube 112 within an inner frame leg 186 and a straight tube 112 in an adjacent outer frame leg 188. FIG. 6 is taken in a direction perpendicular to an interconnection axis 264, which is perpendicular to both the straight tubes 112 in the inner frame leg 186 and the outer frame leg 188. FIG. 6A is taken in a direction which is parallel to the interconnection axis 264. It is noted that a pair of right angle connections 256 are connected to one another, optionally through a straight tube 257, share an interconnection axis 264 about which the connections 256 are connected. Each of the right angle connections 256 is again elbow connections 258 or street connections 260 (as shown in FIG. 1). In general, the interconnection axis 264 extends at an oblique angle relative to the central axis 114 of the hybrid solar heat collector 100.

FIG. 7 is an elevation showing a process for winding a transverse hose 106 around the frame 102, with the frame 102 inverted to upwardly expose openings 270 between adjacent inner frame legs 186 and outer frame legs 188, the process of winding the transverse hose 106 begins with the upper turn 182, having the second connection portion 194 extending outward, in the direction of arrow 278. The transverse hose 106 is wound onto the frame 104 by being moved into the openings 276 to be disposed outside the inner frame legs 186 and inside the outer frame legs 188.

A solar heat collector having a dome-shaped structure built in accordance with a second embodiment of the invention will now be discussed, with reference being made to FIGS. 8-24. FIG. 8 is a perspective view of an alternative dome-shaped structure 300 extending around and over a dome-shaped solar heat collector 302, which is, for example, built as described above in reference to FIG. 5. Alternately, the dome shaped structure 300 may, for example, enclose a dome-shaped solar heat collector built as described above 1-3 and 7. The dome-shaped structure 300 includes a frame 320 having frame members 322 including horizontal frame members 324 and vertically extending frame members 326, intersecting with one another to form a plurality of frame openings 327. The dome-shaped structure 300 additionally includes base members 328 attached to the lowermost horizontal frame members 324 and to a floor structure (not shown). Fluid paths 332 into the solar heat collector 302 extend outwardly through the base members 328.

FIG. 9 is a cross-sectional plan view of the alternative dome-shaped structure 300. Each of the frame members 322 includes slots 334 holding adjacently extending outer translucent sheets 336 and inner translucent sheets 338. A space 342 between the translucent sheets 336, 338 is filled with an aerogel layer 343 and connected to a vacuum sustaining unit 187 through an input line 210. The vacuum sustaining unit 187 operates as described above in reference to FIG. 4A to maintain a vacuum level within the spaces 339. Preferably, the dome-shaped structure 300 includes a vertically extending frame member 326 outwardly adjacent each of the frame elements legs, such as frame legs 223, 224 (shown in FIG. 5), allowing the dome-shaped structure 300 to be placed closer to the solar heat collector 254, since the transverse elements 260 are held inward, extending between adjacent frame elements 258.

FIG. 10 is a transverse cross-sectional view of a frame member 322. Spaces 342 between outer translucent sheets 336 and inner translucent sheets 338 are connected by a channel 340 extending through the frame member 322, allowing air within the spaces 342 to be evacuated simultaneously. Sealing material 344 is provided to prevent or at least minimize a flow of air into the spaces 342. The input tube 172 from a vacuum sustaining unit 167, operating as described above in reference to FIG. 4, is connected to one of the spaces 342 to sustain a vacuum within all of the spaces 342 by the movement of air through channels 340 between the spaces 342. Thus, the individual spaces 342 and the channels 340 are connected to form portions of an internal space 343 a.

For example, the translucent sheets 336, 338 are composed of glass or of a translucent thermoplastic material. The formation of an effective vacuum within the spaces 342 through the use of the vacuum sustaining unit 167 results in the application of significant atmospheric pressures trying to push the adjacent translucent sheets 336, 338 together, but these forces are resisted by the aerogel layer 343 in each of the spaces 342. Shattering may be prevented by attaching an impact resistant film to one or more of the surfaces 345 of the translucent sheets 336, 338. Furthermore, significant strengthening may be achieved by composing either or both of the translucent sheets 336, 338 of a translucent ceramic material.

FIGS. 11 and 12 are transverse cross-sectional views of a frame member 345 showing optional provisions made therein for removing a removable frame section 346, including an outer translucent sheet 336 and an inner translucent sheet 338. Such provisions, which may be made to provide for the removal of one or more removable frame sections 346 for performing maintenance on the heat collector 254, include splitting the frame member 322 into an outer frame member section 348 and an inner frame member section 350, which are held together by a number of screws 352. A gasket 354 is provided around the channels 340 at the interface between the section members 348, 350. Removing the frame member section 346 by loosening the screws 352, provides access through the dome-shaped structure 300.

The dome-shaped structure 300 preferably additionally includes a conduit 358 connecting the central space 156 within the inner dome 162 with a space 166 outside the dome structure 300. For example, the conduit 218 a may carry electrical wires to a power source or a control system. The conduit 218 a prevents the formation of a substantial vacuum within the central space 156 in the event that a leak occurs between one of the internal spaces 342 of the dome-shaped structure 110 and the internal space 148 of the floor structure 126, preventing a possible structural failure of the dome-shaped structure 300.

FIG. 13 is a fragmentary cross-sectional plan view of a lower portion 370 of a dome-shaped structure 372, extending around a lower portion 374 of a solar heat collector 376 built in accordance with another embodiment of a solar heat collector. The solar heat collector 376 includes at least a lower portion built as shown in FIG. 13, with a transverse hose 377 being wound in opposite directions of rotation provide a space 378 between adjacent frame elements 380, through which a person can enter a region 384 within the solar heat collector 376 to enjoy the heat in the manner of a sauna. Similarly, the dome-shaped structure 372 includes at least the lower portion 370 built as shown in FIG. 13 to include an access door 386 pivotally mounted by hinges 388 to be opened in the direction of arrow 390.

The mounting and latching of the door 386 will now be discussed with reference being made to FIGS. 14 and 15. FIG. 14 is a transverse cross-sectional view of a frame member 392 at which the access door 386 is pivoted, taken through one of the hinges 388 joining the frame member 392 and the access door 386. The cross-sectional view is taken perpendicular to an axis of rotation formed by the pins 389. The access door 386 and the frame member 392 are curved outward to present surfaces 393 between a pair of the hinges. Each of the hinges 388 is mounted on spacers 394 so the axis formed by the pins is outwardly disposed from the surfaces 393.

FIG. 15 is a transverse cross-sectional view of a frame member 395 at which the access door 386 is latched. A knob 396, rotatably mounted in the access door 386, is attached to a pawl 400 engaging a latching tab 402 within the frame member 395. When the knob 396 is rotated ninety degrees, the pawl 400 is moved out of alignment with the latching tab 402, allowing the access door 386 to be pivoted open in the direction of arrow 390. A resilient pad 404 may be included to increase a level of force acting between the pawl 400 and the latching tab 402. A handle 405, rotating with the knob 396 is provided for opening the access door 386 from inside the access door 386. While a simple latching mechanism has been described above, it is understood that a conventional latching mechanism of a form well known to those skilled in the art of designing and installing doors, including, for example, a locking knob or latch, could be readily used in this application.

FIGS. 16 and 17 are additional transverse cross-sectional views of the frame member 392, showing an upper end 406 and a lower end 407, respectively, of a tube assembly 408 connecting a space 410 between translucent sheets 412 within the door 386 with a space 342 between translucent sheets 336, 338 adjacent to the door 386. Both the space 410 and the space 342 are filled with aerogel layers 343. The tube assembly 408 includes a formed upper rigid tube 418 connected to the space 414, a formed lower rigid tube 420, connected to the space 416 and a flexible tube 422 extending between the rigid tubes 418, 420. Preferably, the flexible tube 422 is axially aligned with the pivot pin 389 of the hinge 388, so that movement of the door 386 is accommodated by torsional deflection within the flexible tube 422, allowing the space 410 within the door 386 to remain evacuated as the door 386 is opened and closed.

FIG. 18 is a fragmentary perspective view of a dome-shaped structure 440 extending around a solar heat collecting dome 442. For example, the solar heat collecting dome 442 may be built in accordance with an embodiment of a solar heat collector described in detail in U.S. Pat. No. 7,870,855, the disclosure of which is incorporated herein by reference. Both the dome-shaped structure 440 and the solar heat collecting dome 442 are shown with front portions thereof removed to reveal internal details. The solar heat collecting dome 442 includes an opening 444 allowing the direct transmission of radiant solar energy into an internal space 446 within the frame 448 and transverse elements 450 of the dome 442. For example, in the dome 442, the upper plate 268 and the lower plate 270, discussed above in reference to FIG. 6, are replaced with a ring 452 including the opening 444, in which a lens 454 is held. The ring 452 also includes translucent sheet attachment features 455 for the attachment of adjacent translucent sheets 336, 338 within the dome-shaped structure 440. Spaces 342 between translucent sheets 336, 338 extending adjacent one another are filled with an aerogel sheet 343 as described above in reference to FIGS. 8 and 9, with similar features being accorded like reference numbers. These spaces 342 are additionally interconnected, allowing a vacuum sustaining unit 167 to maintain a vacuum level therein through an input line 210, as described above in reference to FIGS. 10-12.

The lens 454 concentrates solar radiant energy on a dish-shaped absorber 456 located, for example at the focal plane of the lens, above a floor structure 458. The dish-shaped absorber 456 absorbs energy that heats the air within the internal space 446, and additionally reflects a portion of the solar radiant energy to heat the frame 448 and transverse elements 450. An electrically-driven fan 452 is preferably additionally provided to circulate air within the internal space 446. Preferably, the dish-shaped absorber 456 is spaced away from the floor structure 458, so that the fan 452 can circulate air both above and under the disk-shaped absorber 456. The dish-shaped absorber 456 may be covered with thermally absorbing and reradiating materials, such as rusty steel plates. The internal space 446 may additionally include a reservoir 460 holding fluid stored at the elevated temperature of the space 446 for later use. The reservoir 460 may be connected to a fluid path within the frame 448, within the transverse elements 450 or elsewhere. Other aspects of the dome-shaped structure 440 and the solar heat collecting dome 442 are as described above in reference to FIGS. 5 and 9.

FIG. 19 is a fragmentary perspective view of an alternative dome-shaped structure 470 extending around and over a solar heat collecting dome 472 including an alternative provision for allowing the entry of radiant solar energy into an internal space 474 within a frame 476 and transverse elements 478 through a ring 480 including an opening 482. For example, the solar heat collecting dome 442 may be built in accordance with another embodiment of a solar heat collector described in detail in U.S. Pat. No. 7,870,855. Again, spaces 342 between translucent sheets 336, 338 extending adjacent one another are filled with an aerogel sheet 343 as described above in reference to FIGS. 8 and 9, with similar features being accorded like reference numbers. These spaces 342 are additionally interconnected, allowing a vacuum sustaining unit 167 (shown in FIG. 18) to maintain a vacuum level therein through an input line 210, as described above in reference to FIGS. 10-12.

FIG. 20 is a perspective view of a dome-shaped structure 500 including brackets 502 supporting elongated members 504 holding a lens assembly 506 in place over the dome-shaped structure 500. For example, the solar heat collecting dome 472, described above in reference to FIG. 19, is disposed within the dome-shaped structure 500, with solar radiation being concentrated on the solar heat collecting dome 472 by the lens assembly 506.

FIG. 21 is a fragmentary cross-sectional elevation of the lens assembly 506, showing an annular frame 508 holding a Fresnel lens 510 in place between a pair of protective translucent sheets 512. While a convex lens can alternatively be used this say, the use of a Fresnel lens provides significant size and weight savings.

FIG. 22 is a plan view of floor portions 520 of the floor structure 521, in an exploded relationship with one another. The floor structure 521 may be added as a part of the dome structures discussed above in reference to FIGS. 8-20. For example, the floor structure 521 has been divided into two floor portions 520 to simplify its transportation. Each of the floor portions 520 includes a flat inner plate 522, shown as partially cut away to reveal details within the floor portion 520, and a flat outer plate 524. The flat plates 522, 524 are composed of a strong and resilient material, such as a metal or a reinforced plastic. A frame 526 holds the flat plates 522, 524 in a spaced-apart relationship with one another, forming an internal space 527 within each of the floor portions 520. Each of the floor portions internal spaces 527 is filled with an aerogel layer 528 holding the flat plates 522, 524 apart when the internal spaces 527 are evacuated. A number of spacers 528 may additionally be provided for this purpose. The floor portions 520 are connected to one another with conventional hardware (not shown), such as screws and brackets, with a connecting tube 530, extending within a gasket 532, connecting the inner spaces 526. A second input tube 534 connects one of the internal spaces 527 with the input tube 172 of the vacuum sustaining unit 167, discussed above in reference to FIG. 4.

Thus, though operation of the vacuum sustaining unit 167, a dome shaped structure (as described above in reference to FIGS. 8-20) and the floor structure 521 become evacuated structures, with air being evacuated from internal spaces 342 of the dome-shaped structure 250 and from internal spaces 527 of the floor structure 521. As the term is used herein, the evacuation of air does not mean that a perfect vacuum is achieved or approximated, but rather that a pressure low enough to substantially reduce the transfer of heat is achieved.

FIG. 23 is a fragmentary perspective view of the dome-shaped structure 300, described above in reference to FIGS. 8 and 9, including a frame 320 holding outer translucent curved sheet 336 and an inner translucent curved sheet 338 within a frame opening 327. The frame 320 and the translucent curved sheets 336, 338 are curved inward, in the direction of arrow 540, and upward, in the direction of arrow 548, but are straight in the direction of arrow 550, extending around the frame 327.

FIGS. 23A and 23B are fragmentary perspective views of alternative versions of the frame 320. In a first alternative frame version 560, shown in FIG. 23A, the frame 560 and the translucent curved sheets 336, 338 are straight in the upward direction of arrow 562, while being curved in the direction of arrow 550, extending around the frame 560. In the second alternative frame version 564, shown in FIG. 23B, the frame 564 and the translucent curved sheets 336, 338 are curved inward, in the direction of arrow 540 and upward, in the direction of arrow 548, and additionally in the direction of arrow 550, extending around the frame 564.

Curving the translucent sheets 336, 338, as shown in FIGS. 23, 243A, and 23B, increases the strength and stiffness of these sheets 336, 338 in resisting the atmospheric pressure applied to these sheets 336, 338 when the space 342 between these sheets 336, 338 is evacuated. In this way, a significant advantage is gained over prior art systems in which flat translucent sheets are used. The curvature of the sheets 336, 338 allows these sheets 336, 338 to be composed of a brittle material, such as glass, or of a flexible material, such as a translucent thermoplastic material, without requiring the use of a multitude of spacers, which in themselves add to thermal conductivity. Furthermore, curving the vertical frame members 326, as shown in FIGS. 23 and 25, increases the strength and stiffness of these frame members 326 in regard to gravitational forces acting on these members 326. It is noted that various curved dome structures have been associated since ancient times with an ability to span relatively long distances within a structure without a need for intervening pillars. The vertical frame members 326 may be curved along a path of a circular arc or along a path, such as a parabolic or catenary path traditionally associated with providing an ability to resist gravitational loading.

FIG. 24 is a partly cut-away plan view of an elongated dome-shaped structure 570, including a number of flat translucent outer panels 336, each of which extends outwardly adjacent a flat translucent inner panel 338, with an aerogel layer 343 extending between the flat panels 336, 338. (It is noted that the panels and the aerogel layers having similar relationships with one another and similar functions are accorded like reference numbers despite variations in the shape of the elements.)

FIG. 25 is a fragmentary cross-sectional view of a panel assembly 574 within the dome-shaped structure 320. The panel assembly 574 includes an outer translucent panel 336, an inner translucent panel 338, and an aerogel layer 343 extending between the panels 336, 338. Because the temperature of the source of solar radiation is so much higher than the temperature of elements within the dome-shaped structure 320, much more radiant heat energy passes through the panel assembly in the inward direction of arrow 576 than outward, opposite the direction of arrow 576, in accordance with the well-known greenhouse effect, allowing the temperature inside the dome-shaped structure 320 to become substantially higher than the ambient temperature outside the structure 320. The effectiveness of the panel assembly 574 in allowing heat energy to be retained within the dome-shaped structure 320 additionally depends on the thermal insulation properties of the panel assembly 574, which reduce the rate at which heat energy is conducted outward, opposite the direction of arrow 576 due to the fact that the temperature inside the dome-shaped structure is substantially greater than the temperature outside the structure 320. In accordance with the present invention, the insulation properties of the panel assembly 574 are provided by using the vacuum sustaining unit 167 to maintain an air pressure low enough to substantially reduce the flow of heat through the space 342 between the panels 336, 338.

The use of coatings of selective materials in accordance with versions of the present invention will now be discussed with reference being made to FIGS. 25 and 26. Such a selective material coating has a thermal emissivity that is substantially lower than its thermal absorption, so that it can be applied to one or more surfaces of a dome-shaped structure to enhance the preferential transfer of radiant energy inward, as needed for the accumulation of heat energy within a solar heat collector inside the dome shaped structure. For example, such a selective material coating is applied to one or both of the outer surfaces 578 of the panels 336, 338. One or both of the panels 336, 338 may be composed of a translucent thermoplastic material, such as polycarbonate, having, for example a selective material sold under the trademark SOLKOTE applied to its outer surface 578 by spraying. Alternatively, a layer of titanium aluminum nitride (TiAlN) may be applied to either or both outer surfaces 578 may by vacuum deposition. It is understood that SOLKOTE has an absorption to emissivity ratio of about 4:1, and that titanium aluminum nitride has an absorption to emissivity ratio of about 20:1.

FIG. 26 is a fragmentary cross-sectional view of a panel assembly 578 built in accordance with a yet another version of the invention to include an outer opaque panel 580, an inner opaque panel 582, and an aerogel layer 583 extending between the panels 580, 582. For example, one or both of the opaque panels 580, 582 is composed of a metal, such as aluminum, or an opaque resin material, having an outer surface 584 with a SOLKOTE coating applied by spraying or a titanium aluminum nitride surface applied by vacuum deposition.

FIG. 26A is a panel assembly 586 built in accordance with still another version of the invention to include a single opaque panel 588 with an outer surface 590 coated with a selective material having an absorption that is significantly greater than it emissivity. It is understood that these selective material coatings may also be applied to a system including one opaque panel and one translucent panel, and that the materials and coatings described in reference to FIGS. 25 and 26 may be applied to panels in the various configurations of the second embodiment of the invention, as described above in reference to FIGS. 8-24.

Referring again to FIG. 1, a selective material coatings as described above regarding FIGS. 25 and 26, may be applied to either or both of the outer surfaces 586 of the outer dome 160 and the inner dome 162, in order to enhance the flow of solar energy into, and to increase the retention of heat within, the central space 156 within the dome structure 110. It is additionally understood that, within the scope of the present invention, either or both of the domes 160, 162 may be composed of an opaque material, such as a metal or resin, which is coated with a selective material.

In accordance with a third embodiment of the invention, a thermally insulating system is provided, including at least one cavity connected to a vacuum sustaining unit and filled with an aerogel. Examples of such insulating systems will now be discussed, with reference being made to FIGS. 27-36.

FIG. 27 is a cross-sectional end elevation of a thermally insulating panel 610 built for use within a thermally insulating structure built in accordance with a third embodiment of the invention to include a plurality of such insulating panels 610 attached to a vacuum sustaining unit 167, as described above in reference to FIG. 4A. The insulating panel 610 includes a pair of side panels 612 held in a spaced-apart condition within a frame 614. An evacuation tube 616 extends through the frame to provide for the evacuation of air from the interior space 618 between the side panels 612, and seals 620 prevent, or at least minimize, the return of air into the interior space 618 following evacuation. In the example of FIG. 27, the side panels 612 are composed of an opaque material, such as a metal, plastic, or composite material including wood chips. Spacers 622 may be attached to extend between the side panels 612, preventing deflection and possible breakage of the side panels 612 due to atmospheric pressure applied by the air around the insulating panel 610. In addition, the side panels 612 are held apart by an aerogel layer 623.

The thermal insulation panel 610 of FIG. 27 is readily useful in architectural applications for separating areas to be held at different temperatures. For example, at least a portion of the interior space within a structure may be thermally isolated from the temperature outside the building, substantially reducing the cost of heating and air conditioning within the building, or a single room may be thermally isolated from other areas in the building. With the active vacuum method of the invention it is practical to provide efficient thermal insulation along large areas using a number of panels 610 within a building, because small leaks, which may occur due to the settling of the building or due to the aging of materials, are taken care of by automatic operation of one or more vacuum sustaining units 167, described above in reference to FIG. 4.

FIG. 28 is a fragmentary front elevation of a thermal insulation system 700 covering a wall 702 and including a number of thermal insulation panels 610, each of which is attached to the inner surface 704 of the wall 702. The evacuation tube 616 of each of the thermal insulation panels 610 is connected to a vacuum sustaining unit 167 through a manifold tube 706. Each of the thermal insulation panels 610 may be covered with a decorative cover 708. The piping, including the manifold tube 706 may be surrounded by conventional insulation 710 to reduce thermal transfer below the panels 610 and is covered by a trim strip 712. The thermal insulation system 700 may be installed after the wall 702 is finished, and may even be applied to an existing building after its construction.

FIG. 29 is a fragmentary front elevation of a thermal insulation system 720 built into a wall 722, and including a number of thermal insulation panels 610. An exhaust tube 616 from each of the insulation panels 610, is attached to a vacuum sustaining unit 167 through a manifold tube 724. The wall 722 includes a number of elongated support members 726. Conventional insulation 730 is placed in various locations not occupied by the panels 610. The wall is additionally covered by a wall board material 732, which is generally shown as cut away to reveal internal details. A front panel 734 of the vacuum sustaining unit 167 extends through the wall board material 730.

While FIGS. 28 and 29 show insulating panels 610 placed against or within walls, it is understood that such panels 610 can readily be placed against or within other elements within a building, such as floors and ceilings, according to the invention.

Versions of the thermal insulation panel 610 may be used within appliances to form internal spaces that can be cooled or heated to a desired temperature with very little transfer of heat to or from the ambient air. For example FIGS. 30-32 show a thermal insulation system 740 within a refrigerator 742, with FIG. 30 being a cross-sectional plan view of the refrigerator 742, and with FIGS. 31 and 32 each being a cross-sectional side elevation thereof. FIG. 31 is taken as indicated by section lines 31-31 in FIG. 30 to show elements within a thermal insulation box structure 744 and in a door insulation panel 746. FIG. 32 is taken as indicated by section lines 32-32 in FIG. 30 to show the pivotal mounting of a door 748 holding the door insulation panel 746 and the connection of an evacuated space 750 within the door insulation panel 746 and an evacuated space 752 within the box structure 744.

Referring first to FIGS. 30 and 31, the thermal insulation system 740 includes a thermal insulation box structure 744 having a pair of thermally insulating side panels 754, a thermally insulating rear panel 756, a thermally insulating top panel 758, and a thermally insulating lower panel 760. An opening 760 at a front side 762 of the box structure 744 is covered by the door 748 when closed, with sealing being provided by a flexible gasket 764 extending around the opening 760. The box structure 744 includes a frame 766 having corner frame members 768 holding panel plates 770 extending in directions perpendicular to one another and front frame members 772 extending around the opening 760, holding panel plates 770 extending rearward. A vacuum is maintained within the evacuated spaces 752 within the box structure 742 through the operation of a vacuum sustaining unit 167, configured as described above in reference to FIG. 4A. Each of the evacuated spaces 752 includes an aerogel layer 753. The input tube 172 (shown in FIG. 4) of the vacuum sustaining unit 167 is connected to the box structure 744 by a connecting tube 774 and to the various evacuated areas 752 within the box structure 744 by openings 776 extending through the corner frame members 768. The refrigerator 742 includes conventional elements, such as an external cover 778, an internal cover 780 and a door cover 782.

Referring to FIG. 32, the door 748 is pivotally attached to the main portion 784 of the refrigerator 742 by means of an upper pin 786 extending downward from an upper bracket 788 and a hollow lower pin 790 extending upward from a lower bracket 792. The space 750 within the door insulation panel 746 is connected to a space 752 within one of the thermally insulating side panels 744 by a flexible tube 794 extending through the hollow lower pin 790, so that the opening and closing motion of the door 748 is accommodated by twisting an elongated portion 796 of the flexible tube 794, with the elongated portion 796 preferably being coaxially aligned with the pins 786, 790. The space 750 is filled with an aerogel layer 751.

FIG. 33 is a cross-sectional plan view of a container 800 including an evacuated structure 802 including a box structure 804 having an access opening 804 at a rear end 806 and a pair of door structures 808. The container 800 may be of the type that is loaded on a ship, a railroad car, or on a truck trailer. Alternately, the container 800 may form a permanent part of a truck trailer. Each of the door structures 808 is disposed within a door 810 of the container 800, with the door 810 being pivotally mounted by a hinge 812 to moved between the closed position in which it is shown and the open position indicated by dashed lines 814. The evacuated structure 802 is composed of a number of panels 610, which are generally constructed as described above in reference to FIG. 27. Preferably, the panels 610 extend along each side 820 of the container 800, along the front end 822 thereof, along the floor 824 thereof, and along the ceiling (not shown) thereof, being inwardly disposed, and attached to, structural elements of the container 800, such as ribs 826. All of the internal spaces 618 of the panels 610 are filled with aerogel layers 623 (as shown in FIG. 27) and are connected to one or more vacuum sustaining units 167, discussed above in reference to FIG. 4A, which may be located inside the container 800, as shown, or outside the container 800.

FIG. 34 is a first fragmentary cross-sectional elevation of the container 800, showing a first method for connecting the internal spaces 618 to a vacuum sustaining unit 113. Each of the panels 610 includes an evacuation tube 830, which is connected to a manifold tube 832 extending along a corner of the box structure 804. All of the manifold tubes 822 are connected to the vacuum sustaining unit 167, with the connections being made, for example, by welding or by screw thread attachment.

FIG. 35 is a second fragmentary cross-sectional elevation of the container 800, showing a second method for connecting the internal spaces 618 to a vacuum sustaining unit 167. The internal spaces 618 within adjacent panels 610 are connected through a tube 834 extending through a gasket 836 At least one of the panels 610 is directly connected to a vacuum sustaining unit 167. Internal spaces 618 within the door structures 808 are connected to internal spaces 618 within the box structure 804 by flexible tubes extending in alignment with the hinges 812 as described above in reference to FIGS. 30-32.

The vacuum sustaining unit 167 may be operated through the use of a rechargeable battery that is plugged into the electrical system of a truck carrying the container. Furthermore, the container 800 may additionally include a refrigeration system (not shown) sharing a power source with the vacuum sustaining unit 167. Alternatively, the unit 167 may not be provided with the container 800, with an external connection to a manifold tube 832 being instead provided for periodic use of an external version of the vacuum sustaining unit 167.

FIG. 36 is a cross-sectional plan view of a railroad car 850, which is, for example, an insulated boxcar or refrigerator car, in which an insulating structure 852 is installed. This insulating structure 852 is similar to the insulating structure 802 within the container 800, described above in reference to FIG. 33, except that different provisions are made for the access doors 854, each of which includes a door structure 856 having thermally insulating panels 610. Each access door 854 is movably mounted using standard railroad car hardware providing a plug-door arrangement, in which the access door 854 is moved outward before being slid along a track 858 for opening, and closed by being moved inward after sliding along the track 858. In the figure, the access door 854 in a first side 860 of the railroad car 850 is shown in a closed position, while the access door 854 on a second side 862 of the railroad car 854 is shown in an open position, so that access is provided through an opening 864

The insulating panels 610 within each of the door structures 856 are connected with the insulating panels 610 within a box structure 860 by means of a flexible tube 864 resting within a tray 866. Preferably, the tray 864 is installed near the roof of the railroad car 850, with the tubes 862 being attached near the top of the doors 854.

While the invention has been shown in its preferred embodiments and versions with some degree of particularity, it is understood that this description has only been given by way of example, and that many changes can be made without departing from the spirit and scope of the invention, as defined by the appended claims. 

1. A thermally insulating system comprising: a thermally insulating structure including an internal space formed by internal surfaces; an aerogel layer extending between at least parts of the internal surfaces within the internal space; a vacuum sustaining unit including a first input tube connected to the internal space, a pressure sensor sensing a pressure within the internal space; and a vacuum pump evacuating air from the internal space in response to a signal from the pressure sensor indicating that a pressure within the internal space has risen above a predetermined level.
 2. The thermally insulating system of claim 1, wherein the thermally insulating structure includes a floor structure and a dome-shaped structure, extending upward from the floor structure, the dome-shaped structure includes an internal surface forming a central space extending from the internal surface to the floor structure, and an external surface, the internal space extends within the dome-shaped structure, separate from the central space and between the internal and external surfaces, and the dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure.
 3. The thermally insulating system of claim 2, wherein the dome-shaped structure comprises: an inner dome including a dome-shaped portion having an inner surface forming the internal surface, an outer surface, and a lower surface, with a lower flange extending outwardly around the lower surface; an outer dome including a dome-shaped portion having an inner surface, an outer surface forming the external surface, and a lower surface, upwardly disposed from the lower flange of the inner dome, with an upper flange extending outwardly around the lower surface of the outer dome; a gasket extending between the lower flange and the upper flange to enclose a space extending between the inner and outer translucent domes to form the internal space; and at least one bracket holding the inner and outer translucent domes in a spaced-apart relationship.
 4. The thermally insulating system of claim 3, wherein the dome-shaped portions of the inner dome and the outer dome are each composed of a translucent material, and at least one of the outer surfaces is coated with a selective material having a thermal absorption and a thermal emissivity, and the thermal absorption of the selective material is significantly greater than the thermal emissivity of the selective material.
 5. The thermally insulating system of claim 3, wherein at least one of the dome shaped portions is composed of an opaque material, at least one of the outer surfaces is coated with a selective material having a thermal absorption and a thermal emissivity, and the thermal absorption of the selective material is significantly greater than the thermal emissivity of the selective material.
 6. The thermally insulating system of claim 2, wherein the dome-shaped structure comprises; a dome-shaped framework including a plurality of frame openings; an inner sheet and an outer sheet held within each frame opening within the plurality of frame openings, wherein the inner and outer translucent sheets are held in a spaced-apart relationship to form a portion of the internal space, and wherein an aerogel layer extends within the portion of the internal space; and a plurality of openings connecting the portions of the internal space in adjacent frame openings to form the internal space.
 7. The thermally insulating system of claim 6, wherein the dome-shaped framework additionally comprises a door section mounted to be moved between an open position and a closed position, and a flexible tube extending between the door and an adjacent surface of the dome-shaped framework; access from outside the dome-shaped structure to the central space within the dome-shaped structure is provided with the door section in the open position and prevented with the door section in the closed position the door section extends around one of the frame openings, the door section holds the inner and outer sheets within the frame opening in the door section, and the flexible hose connects the portion of the internal space between the inner and outer translucent curved sheets within the frame opening in the door section with the portion of the internal space within an adjacent frame opening.
 8. The thermally insulating system of claim 6, wherein the dome-shaped framework additionally includes an opening through which a lens concentrates solar radiation within the central space.
 9. The thermally insulating system of claim 6, wherein the inner sheet and the outer sheet held within each frame opening are composed of a translucent material, at least one of the outer surfaces is coated with a selective material having a thermal absorption and a thermal emissivity, and the thermal absorption of the selective material is significantly greater than the thermal emissivity of the selective material.
 10. The thermally insulating system of claim 6, wherein at least one of the inner and outer sheets held within each frame opening is composed of an opaque material, the inner and outer sheets held within each frame opening each have an outer surface, at least one of the outer surfaces is coated with a selective material having a thermal absorption and a thermal emissivity, and the thermal absorption of the selective material is significantly greater than the thermal emissivity of the selective material.
 11. The thermally insulating system of claim 2, wherein the floor structure includes: a flat inner plate composed of a strong and resilient material; a flat outer plate composed of a strong and resilient material; a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an inner space extending within the frame and between the flat inner and outer plates; an aerogel layer held within the inner space extending within the frame and between the flat inner and outer plates; and a second input tube connecting the inner space within the floor structure with the vacuum sustaining unit.
 12. The thermally insulating system of claim 2, additionally including a conduit connecting the central space with an external space.
 13. The thermally insulating system of claim 1, wherein the thermally insulating structure comprises a plurality of thermally insulating panels, each of the thermally insulating panels includes a flat inner plate composed of a strong and resilient material, a flat outer plate composed of a strong and resilient material, and a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an inner space extending within the frame and between the flat inner and outer plates, a portion of the aerogel layer extends between the flat inner plate and the flat outer plate within each of the thermally insulating panels and the interior space within each of the thermally insulating panels is connected to the vacuum sustaining unit.
 14. The thermally insulating system of claim 13, wherein the interior space within each of the thermally insulating panels is connected to the vacuum sustaining unit by a common evacuation tube.
 15. The thermally insulating system of claim 13, wherein interior spaces within adjacent thermally insulating panels are connected by openings extending through adjacent portions of the frames within the adjacent thermally insulating panels.
 16. The thermally insulating system of claim 13, wherein the thermally insulating panels form a box structure, extending around a central space, and a door structure, the box structure includes a first access opening. the door structure is movable between a closed position, extending within the first access opening, and an open position, access into the central space is provided with the door structure in the open position and prevented with the door structure in the closed position, and the door structure includes one of the thermally insulating panels, connected to the vacuum sustaining unit by a path including a flexible hose.
 17. Solar heating apparatus comprising: a heat receiving structure through which a fluid flows to be heated by solar radiation; and a thermally insulating structure, including a floor structure and a dome-shaped structure, extending upward from the floor structure, wherein the dome-shaped structure includes an internal surface forming a central space holding the heat-receiving structure and extending from the internal surface to the floor structure, and at least one outward-facing surface coated with a selective material having a thermal absorption and a thermal emissivity, wherein the thermal absorption of the selective material is significantly greater than the thermal emissivity of the selective material.
 18. The solar heating apparatus of claim 17, additionally comprising: an evacuated internal space extending within the dome-shaped structure, separate from the central space and between the internal and external surfaces, wherein the evacuated internal space is at least partly filled with an aerogel layer, and wherein the dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure; and a vacuum sustaining unit including a first input tube connected to the internal space, a pressure sensor sensing a pressure within the internal space; and a vacuum pump evacuating air from the internal space in response to a signal from the pressure sensor indicating that a pressure within the internal space has risen above a predetermined level.
 19. The solar heating apparatus of claim 18, wherein the floor structure includes: a flat inner plate composed of a strong and resilient material; a flat outer plate composed of a strong and resilient material; a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an evacuated inner space extending within the frame and between the flat inner and outer plates, wherein the evacuated inner space is at least partly filled with an aerogel layer, and wherein the evacuated inner space is connected to the vacuum sustaining unit.
 20. The solar heating apparatus of claim 18, additionally including a conduit connecting the central space with an external space. 